---
id: suite-harness-current-thread
name: Contract-suite harness — async sleep in `past_stamp_sleep`, current-thread flavor readiness
status: pending
depends_on: []
scope: narrow
risk: low
impact: component
level: implementation
tags: [wave-6, contract-suite]
---

## Description

The one suite-side change wave 6 carries
([ADR-024](../architecture/decisions/024-mem-engine.md) §5 item 4; the
review-003 posture note at `properties.rs:1683`): the suite's
`past_stamp_sleep` helper uses a blocking `std::thread::sleep` inside
async rows — safe under the multi-thread test flavors both existing
engines' targets use, but it would stall a current-thread runtime. The
mem engine's suite column **must** run under a current-thread flavor
(`#[tokio::test(flavor = "current_thread")]`) to keep the mem
engine's internals honestly current-thread-clean — which is what
wasm32 needs.

- Replace `past_stamp_sleep`'s blocking sleep with `tokio::time::sleep`
  (async). The helper's semantics are unchanged (a bounded
  pre-`run_at` settle before reads); the existing rows' determinism
  posture is untouched — verify the two legs using it re-run green on
  both engines with no timing drift (tolerances unchanged).
- Document (one line in the helper's doc comment or the factory
  contract notes) the harness posture: **no blocking calls inside
  suite rows** — the mem column enforces the flavor that catches
  violations.

This task is engine-independent and can run any time before
`mem-engine-integration` wires the third column.

## Acceptance Criteria

- [ ] `past_stamp_sleep` is async (`tokio::time::sleep`)
- [ ] Both engines' existing suites re-run green with identical
      assertions and tolerances (determinism posture intact)
- [ ] The no-blocking-calls posture noted where the harness's
      determinism posture is documented
- [ ] Clippy `-D warnings`, fmt clean; workspace gates green

## References

- docs/architecture/decisions/024-mem-engine.md §5
- docs/reviews/003-wave-5-general-review.md §Finding 5 (the
  `properties.rs:1683` posture note)
- docs/architecture/decisions/022-contract-suite-layout.md (the
  factory contract the flavor rides)

## Notes

> To be filled by implementation agent

## Summary

> To be filled on completion